The construction of furniture and other objects from wood or wood-like materials requires the joining of different, individual pieces. Such methods have evolved over thousands of years. More basic methods of joining involve the insertion of metal objects between the two pieces, such as nails or screws. A more artful joining method utilizes a dowel inserted into a hole common to both pieces. The most elegant joining methods however, involve forming the pieces themselves into tightly fitting, interlocking shapes. Such methods include dovetail joints and mortise and tenon joints.
The utilization of mortise and tenon joints is well known in the art, particularly in the creation of wooden furniture. Mortise and tenon joints can be classified by the angle from which the tenon work piece extends from the mortise work piece (ninety degree, angled, or compound angled). The prevalence of such joints has led to various methods and apparatuses for creating mortises and tenons. The quicker methods take advantage of power tools such as routers. The router bit is guided around a piece of wood to shape the desired tenon.
One such method and apparatus is set forth in U.S. Pat. No. 4,479,523 issued to Peterson et al. While providing an accurate method for generating a mortise and tenon, the Peterson et al. invention requires a number of varying templates, a stage, stops, blocks, and clamps. Compound angle joints in particular require the creation of a "double angle stop block" to arrange the work pieces at the desired compound angle. The device of the '523 patent requires the work piece to be secured to the stage, against a stop by a number of clamps and an angled block if necessary. A first router pass machines half of the tenon. The template is then flipped, and a second pass finishes the tenon. This apparatus and method lacks versatility as well as requiring substantial setup time and sizable equipment.
A second system is illustrated by U.S. Pat. No. 4,749,013 issued to Ducate, Sr. The woodworking machine set forth in this patent utilizes a first tiltable stage that is capable of movement along two orthogonal horizontal axes, and a second, adjacent, vertically disposed stage, capable of movement along a vertical axis. The second stage contains a rotary motor and a perpendicularly projecting stylus. The woodworking machine can be prepared to machine tenons by equipping the rotary motor with a router bit and attaching a template to the first stage so that it is disposed parallel the second plane. The work piece is clamped to the first stage, and the first stage tilted and otherwise moved about the horizontal plane for proper alignment with the router bit. The first and second stages are then manipulated to guide the stylus within, or around the template to machine the desired shape. This woodworking system requires sizable equipment and set up time. The work piece must be aligned with a remotely positioned stylus and template, and both stages must be moved to accomplish the machining. This complicates the task of machining.
An article by Patrick Warner, titled "End-Work Router Fixture" appearing in Fine Woodworking, September 1992, sets forth an apparatus for machining the end of a board. This device includes a router platform having a window and a clamping board with an indexing fence. The device can generate angled tenons, but not compound angle tenons. The generation of varying tenons also requires a large overlay template for each different tenon on the platform, or variably sized routers. This lack of versatility makes the creation of differently shaped tenons a complicated endeavor.
None of the prior art sufficiently addresses the need for a simple and versatile mortise and tenon generating system having a minimal number of components.